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Two BOG treatment processes are adopted in the Tangshan LNG terminal of PetroChina, including the recondensation and highpressure compression based export processes. However, the LNG cold energy could not be fully used if only the high-pressure compression method is used for BOG treatment in the low export condition. The booster compressor has high operation power and large energy consumption.For this reason, the combined BOG treatment scheme of the Tangshan LNG terminal was studied through the combined numerical simulation and theoretical research with the ASPEN HYSYS software. Meanwhile, the combined operation scheme of the re-condenser and booster compressor was formulated to make full use of the LNG cold energy and reduce the operating power consumption of the booster compressor. The results show that the BOG flow has a great impact on the downstream LNG temperature. To control the downstream LNG temperature change of the re-condenser, the BOG flow should be controlled at first, with the auxiliary of BOG temperature and LNG header flow control. The combined operation scheme after optimization could reduce the power consumption of the compressor by 5%-20%, so that about 9.4×105 kW·h power can be saved annually, with an obvious optimization effect. Generally, the research results could provide a theoretical reference for the calculation of the combined BOG treatment process in the LNG terminal and the formulation of the operation scheme.

The behaviour of individual abalone in a population is known to vary, and higher levels of activity are linked to better survival rate and faster growth. Considering that continuous illumination at night may cause stress to the abalone which would affect their behaviour over time, in this study observations were made under brief and minimal illumination. The observation lasted for 30 days. The relationships between activity traits were analysed in juvenile Haliotis discus hannai Ino, such as forage frequency, duration and trajectories; flow preference; and aggregation size. The aim was to identify an indicator of the abalone activity status, with the ultimate objective being to provide activity‐related data that might be useful in farm rearing. Ten traits related to locomotion behaviour of 47 juvenile abalone were recorded under laboratory conditions. The results showed that the exploratory level varied between individuals. More exploratory individuals foraged more frequently, spent more time outside hides, started foraging earlier and preferred higher water flow rate than less exploratory individuals. More exploratory and less exploratory individuals also differed in their extensive movements, hide‐shift frequency and aggregation size. [ABSTRACT FROM AUTHOR]

The complete mitogenome of Haliotis iris, an economically important shellfish endemic to New Zealand, was sequenced for the first time. The mitogenome was 17,131 base pairs (bp) in length and contained 13 protein-coding genes (PCGs), 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes and a control region. All 13 genes were initiated by the start codon ATG, except for nad5 (ATA). Two typical stop codons, TAA and TAG, were present. All of the tRNAs could be folded into typical cloverleaf secondary structures except tRNASer1 and tRNALys, which lacked a DHU stem and complete amino acid acceptor stem, respectively. The control region was 1132 bp in length and contained six AT tandem repeats. According to the gene order of the mitogenome, the 30 analysed Vetigastropoda species could be classified into three types—type I: over half of the studied species were very similar to the gastropod ancestral gene order, and the rearrangements occurred in five tRNAs; type II: eight species were found to be missing several tRNA genes; type III: Fissurellidae, Lepetodrilidae showed a large inverted fragment. [ABSTRACT FROM AUTHOR]

The black-footed abalone Haliotis iris is an economically important shellfish species in New Zealand. We successfully amplified, sequenced and analysed the complete nuclear ribosomal DNA (nrDNA) of H. iris. The length of the nrDNA was determined to be around 9.6 kb and included, in order, small subunit ribosomal RNA (nrSSU, 1858bp), internal transcribed spacer (ITS, 749 bp), large subunit ribosomal RNA (nrLSU, 3412bp) and an intergenic spacer (IGS, 3560-3662 bp). The nrLSU genes were identical in two individuals, whereas the nrSSU and ITS regions existed at three and four base differences, respectively. The IGS was more variable than the other nrDNA regions. A phylogenetic tree was constructed based on the ITS sequence datasets, which revealed that Haliotidae has two major subclades, mainly distributed in the North Pacific, Europe and Australia. The complete nrDNA sequence will be useful for the classification, phylogeny and breeding of this shellfish. [ABSTRACT FROM AUTHOR]

Chlamydomonas sp. ICE-L, which can thrive in extreme environments of the Antarctic, could represent a promising alternative for polyunsaturated fatty acid (PUFA) production. A new Δ12-fatty acid desaturase (FAD)-encoding gene (Δ12CiFAD), 1269 bp in size, was cloned from Chlamydomonas sp. ICE-L. Bioinformatics analysis showed that Δ12CiFAD-encoded protein was homologous to known FADs with conserved histidine motifs, and localized to the chloroplast. Functional analysis of Δ12CiFAD indicated that recombinant Synechococcus 6803 expressing Δ12CiFAD could accumulate C18:2, whereas recombinant Saccharomyces cerevisiae expressing this enzyme could not accumulate C18:2 or any other new fatty acids. These results indicate that Δ12CiFAD is a functional enzyme in the chloroplast that can adjust Chlamydomonas sp. ICE-L cell membrane fluidity to adapt to Antarctic extreme low-temperature environments, which give us insights into the frigostable and cold-resistant mechanisms of hypothermic organisms. [ABSTRACT FROM AUTHOR]

Perna viridis and P. canaliculus are economically and ecologically important species of shellfish. In this study, the complete ribosomal DNA (rDNA) unit sequences of these species were determined for the first time. The gene order, 18S rRNA-internal transcribed spacer (ITS) 1-5.8S rRNA-ITS2-28S rRNA-intergenic spacer (IGS), was similar to that observed in other eukaryotes. The lengths of the P. viridis and P. canaliculus rDNA sequences ranged from 8,432 to 8,616 bp and from 7,597 to 7,610 bp, respectively, this variability was mainly attributable to the IGS region. The putative transcription termination site and initiation site were confirmed. Perna viridis and P. canaliculus rDNA contained two (length: 93 and 40 bp) and one (length: 131 bp) repeat motifs, respectively. Individual intra-species differences mainly involved the copy number of repeat units. In P. viridis , three cytosine-guanine (CpG) sites with sizes of 440, 1,075 and 537 bp were found to cover nearly the entire IGS sequence, whereas in P. canaliculus , two CpG islands with sizes of 361 and 484 bp were identified. The phylogenetic trees constructed with maximum likelihood and neighbour-joining methods and based on ITS sequences were identical and included three major clusters. Species of the same genus were easily clustered together., Competing Interests: The authors declare that they have no competing interests.

Objective: The complete genome of the agarolytic bacterium Pseudoalteromonas sp. NJ21 from Antarctic sample was analyzed by bioinformatics methods and putative agarase aga3311was screened. Expression and characterization of the putative agarase aga3311 were studied., Methods: Gene aga3311 was cloned and expressed by genetic engineering method firstly; then, the recombinant enzyme was purified by Ni-NTA chromatography and the characterization of recombinant enzyme was determined by dinitrosalicylic acid method; the hydrolysis product of recombinant enzyme Aga3311 was analyzed by thin-layer chromatography (TLC) and mass spectrometry (MS)., Results: The recombinant expression vectors (pET-30(a)+aga3311) was overexpressed in E. coli BL21(DE3) and 30% of the recombinant protein was soluble. The purified agarase (Aga3311) revealed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular weight of 87 kDa. The optimum temperature of the recombinant agarase was 35℃, and it maintained higher activity between 30 and 45℃, but the activity declined rapidly above 50℃, typical of thermal instability enzyme. The optimum pH was 7.0, and it maintained 50% of its maximum activity between pH 4 and 10. Aga3311 was significantly activated by Fe3+, Be2+, Zn2+ and Ca2+, especially Ca2+ doubled the enzyme activity. The pattern of agar hydrolysis of Aga3311 is an exo-β-agarase, producing neoagarobiose (NA2) as the final main product., Conclusion: Aga3311 is an exo-β-agarase of Glyco_hydro_42 family, producing neoagarobiose (NA2) as the final main product.